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83 GMC half ton- CANNOT SOLVE MY VIBE PROBLEM

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Can Can, Jan 17, 2003.

  1. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Hey brothers!!! My "other ride" is a 83 1/2 ton(6.2, 700r4, 3.42s). About 4 years ago, I replaced my driveshaft support bearing and my rear u-joint. Ever since then, I've had a relatively subtle vibration that comes on at about 40 MPH and disappears at 60 MPH. The vibe also happens if I pop the tranny into neutral at those speeds so it has to be driveline related.

    I've checked and rechecked absolutely every possible cause of the vibration. I've even replaced my tires. All the u-joints look good and have been greased on a regular basis. I doesn't look like the driveshaft has dropped any balancing weights, either.

    I'm starting to think that I'll never solve this problem. Could someone start throwing ideas at me? Thanks, brothers.
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Maybe the driveshaft is now out of phase after replacing the steady bearing?

    Rene
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Sorry, Rene, everything checks out there as well. My driveshaft is a 2-piece unit, and there's a master spline so you can't get out of phase when you put things back together....

    Anybody else want to take a try?
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    So you replaced the steady bearing and one U-joint?

    If so i'd replace the rest of the U-joints on that shaft and see how it is. I've had U-joints that appeared good be real close to failure and vibed...

    Rene
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I think that's my next step. I've also had u-joints that appear next-to-new while still on the driveshaft and ended up being seized or worn once removed from the truck.

    I'm willing to bet that I replaced the original worn u-joint with a bad one right out of the factory and that's been the cause of the vibe since day one.
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I had a vibe start once just outside of San Francisco when we were towing our trailer home a few years ago. I stopped and checked out the U-joints as best I could and had no indication one was bad. I thought maybe a bad motor mount or who knows what and finished driving home. By the time we got home the U-joint was done and by then it was obvious...

    Rene
     
  7. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    See, that makes sense. The wierd part about my vibe issue is that it started about 60,000 kms ago and hasn't got any worse, even with all the towing I've done.... /forums/images/graemlins/crazy.gif

    I'm glad you visit this forum, Rene. Apparently the 2WD guys have good jobs that offer lots of vacation time!!!/forums/images/graemlins/wink.gif
     
  8. drivelineman

    drivelineman 1/2 ton status

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    Okay on this problem chevy's are prone to aftermarket carrier bearing problems- especially s-10's with 2 piece driveline's - we have actually found the factory carrier bearing is a different material and does make a difference on vibration level sometimes a big difference - now here's the funny part the carrier bearing aftermarket is aprox. 18$ and from chevy its about 70$ wow what a difference no wonder everyone goes aftermarket- but believe me it does make a difference especially if yours vibrates from 25 mph and over- i would change the carrier or at least the rubber piece you can buy seperatly and rebalance the shaft - please let us know if that fixes it- remember to use factory chevy stuff - Jesse
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'd listen to the pro...Jesse certainly knows a hell of a lot more about this stuff than I do.

    Rene
     
  10. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Jess: By "carrier bearing" are you referring to the driveshaft support bearing? And why do you recommend rebalancing the driveshaft even though there's no been no damage done to it? How much would it cost me to get the shaft balanced?

    Rene: Don't sell yourself short, brother!!!
     
  11. drivelineman

    drivelineman 1/2 ton status

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    Yes sir the support bearing - you got it- and as for balancing the shaft its crutial becuase you have 3r series joints - meaning nylon injected factory -(not my favorite) /forums/images/graemlins/smile.gif anyways they are set factory then injected not really centered up and when you change them the wieghts are in the wrong spot because things are not in the same place - basically the placing of the nylon and centering on joints is sloppy from aam- or mm knoff -or 3r rivers michigan there all the same to me- /forums/images/graemlins/smile.gif - now for balancing i recomend running the shaft at resonence speed of the carrier bearing and tunning it there , this should make sense to the driveline shop , aprox. 1700rpms that's where the drivline gets excited -or resonence frequiency or 25 mph depending on gear ratio and tire size- and so on- and tell them to do that and not to worrie about higher spped unbalances becuase the oem rubber carrier will dampen those frequincies - this may seem ubsurd but its all good /forums/images/graemlins/thumb.gif
    please let us know on results- or have your driveline shop call me - thanks and good luck- i hate thise type of shafts there picky- Jess
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    </font><blockquote><font class="small">In reply to:</font><hr />
    Rene: Don't sell yourself short, brother!!!

    [/ QUOTE ]

    I'm not Paul, but I know for a fact Jesse has forgotten more about driveline tech than I'll ever know. There is no point of pride here...only that you get the best quality advice possible/forums/images/graemlins/thumb.gif

    Rene
     
  13. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Ok, I think I understand, Jess. Basically, by changing out a u-joint you alter the balance of the shaft because the specs of aftermarket u-joints are a little different then the ones from the factory. Is that right?

    But here's a question- I've swapped out the u-joints on the rear shaft of my K5 and I have no vibe issues. Does it happen on 2WDs because of the 2-piece driveshaft?

    Thanks a lot for your input Jess. You never told how much all this balancing was going to cost- c'mon, spill the beans!!!! /forums/images/graemlins/grin.gif
     
  14. KShortell

    KShortell Registered Member

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    I went through something similar in my Suburban.

    I replaced U-joints, carrier bearing, had the driveshaft custom balanced ($150, by the way), replaced shocks, balanced tires, replaced a rim, bought all new matching lugnuts, replaced tranny and motor mounts, tuned up engine, replaced lower ball joints-- all to no avail.

    It ended up being the flexplate on the back of my 350. One of the torque converter mounting holes had dimpled out a bit! See here for more: 350 Flexplate replacement on a 1986 Suburban

    BTW, on a TH700R4-equipped 4x2, you cannot get the driveshaft out of phase. The yoke at the transmission is keyed and can only be installed one way, unlike the 4x4s. I like that! /forums/images/graemlins/thumb.gif

    Good luck! Be patient- took me 6 years to cure mine... /forums/images/graemlins/blush.gif
     

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